Bearing drag on Poly Wheel for my 2"x72"

You know it is very easy to replace the bearings and drop a sleeve in there, I can't remember the bearing size for the wheels but it is about $11 each for good-high quality, and all you need for a sleeve is a piece of tubing that is the right size to fill the space between the 2 bearing and only sit on the inner race.

I am most likely going to take my grinder apart in the next couple of weeks to get the upright welded in place, so I may just take the time to replace my bearings and sleeve the wheels at the same time.
 
This place has a good selection of bearings and they have ceramic hybrid bearings as well as full ceramic bearings. I think the hybrids would be a really good option for a grinder especially the smaller wheels that are spinning at higher RPM.

www.bocabearings.com
 
You know, I did some experimenting with ceramic bearings, on bike wheels, and found that they really didn't make that much of a difference in that application. Yes if you look at it on paper there is an improvement, but on the road it was so small that you couldn't feel anything or see any improvement on the clock with them. Now I admit that I am not a high performance athlete and any time clocks we had were not calibrated fine enough and were operated by a person so the timing wasn't even a factor. The real factor was the price vs improvement. For the money that I would have had to pay for ceramic bearings in my bike wheels, there would have needed to be a visual improvement in performance. Ceramics bearings can be a bit on the brittle side and to gain any real measure of performance the races would have to be ceramic too, pushing the price up to nearly $100 each:eek:

For our general use a good ABEC5 or higher bearing will pretty much hit the value/performance nail on the head.
 
Before I retired, I was a mechanical engineer that designed high speed rotating systems to control satellite attitude. Bearings come in all types and the ones typically used in the wheels being discussed are called radial or deep groove. They are designed to maximize radial load capacity but do not like much axial load and can fail very quickly when subjected to it. If things are getting really hot, it will quickly destroy the lubricant and cause rapid failure. The comments about adding a sleeve between the inner races are absolutely correct, assuming at least one outer race can move. If the outer races are both pressed in, the sleeve would have to be a perfict fit between the inners to prevent axial loading. If you are unhappy with the play that results when you remove the axial load there is another option. Angular contact bearings are designed to be loaded axially to take out play and are used in high precision applications such as surface grinder spindles. They are generally more expensive and have to be mounted properly but they will eliminate most play. Lower quality ones such as ABEC 3 would be fine on a grinder application.

Hybrid bearings (ceramic balls and steel races) are indeed very tough and can survive in environments and with loads that will quickly kill regular bearings. They were used in the pumps that move fuel into the space shuttle main engine because conventional steel bearings would have only lasted seconds at best at the temperatures, speeds and poor lubrication conditions present. Frankly, I think they would be overkill for a grinder but they would definitely work. They would still need to be mounted correctly to get proper running temp and life.
Randy
 
Well.... I'll try to go back to the bearing wholesaler today and see if they have those sleeves in 1-1/2"ish widths. I left my wheel home so don't know the exact width. I assume the bearings are close to 1/4" each so if I go 1-3/4" I can grind them down to size.

I have an expansion tool that I use to slide inside copper water lines to seal the water from coming out the pipe while I solder on a new valve, I'll use that tool to see if I can knock out the bearings w/o damaging them.
The "hardest" part is finding a sleeve. Not too worried about putting them in.
Are the bearings in the wheels now abec 5?

Also, while I'm at it, on the other thread about skateboard wheels, someone uses bearing to make small wheels.... I imagine I should see about making some of those too....

George, can I steal your tag line? Lol... I can't stop buying new stuff.... keep looking at Power hammers and presses now.....and anvils, and vises, and................................can't forget hammers and tongs.....;)
 
fluidsteel said:
the other thread about skateboard wheels, someone uses bearing to make small wheels

.... I imagine I should see about making some of those too....
Click to expand...

That's the KMG style small wheel


http://www.beaumontmetalworks.com/kmg-swa.html
smwheel5.jpg


Notice the huge mass of aluminum acting as a heat sink for the bearings.

I think running lower speeds, avoiding improper tension and getting the heat away from the bearings is key for bearing life.
 
Last edited:
12345678910 said:
That's the KMG style small wheel


http://www.beaumontmetalworks.com/kmg-swa.html


Notice the huge mass of aluminum acting as a heat sink for the bearings.

I think running lower speeds, avoiding improper tension and getting the heat away from the bearings is key for bearing life.
Click to expand...

I'm running a VFD from Wayne Coe, so I'll be running slower speeds as I develop my grinding skills. I figure with my calipers I can size the sleeve maybe a few thousandths over and the bearings will just seatbslightly out from the inner stepped shoulder on the wheel.
 
fluidsteel said:
Well.... I'll try to go back to the bearing wholesaler today and see if they have those sleeves in 1-1/2"ish widths. I left my wheel home so don't know the exact width. I assume the bearings are close to 1/4" each so if I go 1-3/4" I can grind them down to size.

I have an expansion tool that I use to slide inside copper water lines to seal the water from coming out the pipe while I solder on a new valve, I'll use that tool to see if I can knock out the bearings w/o damaging them.
The "hardest" part is finding a sleeve. Not too worried about putting them in.
Are the bearings in the wheels now abec 5?

Also, while I'm at it, on the other thread about skateboard wheels, someone uses bearing to make small wheels.... I imagine I should see about making some of those too....

George, can I steal your tag line? Lol... I can't stop buying new stuff.... keep looking at Power hammers and presses now.....and anvils, and vises, and................................can't forget hammers and tongs.....;)
Click to expand...

Unfortunately I can almost guarantee that you wont be able to get the bearings out without damaging them if they look anything like mine:( There is no way I could get anything on the outside race to pop them out, one of the reasons I haven't changed them yet. I figure that if I am going to kill them I might as well do it from use. I do check my wheels before each use to make sure they are still spinning with no indexing.
 
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